Thousands are expected to surround the White House Sunday afternoon to oppose the controversial Keystone XL Pipeline.
350.org, which organized the event, wants President Obama to uphold his promise to prevent the oil pipeline, which would stretch from Alberta, Canada to the Gulf of Mexico, from being built. The President stopped plans for the pipeline earlier this year, citing environmental reasons. Some Republicans criticized the decision, saying the building of the pipeline could bring thousands of jobs.
Sunday's event is part of a national tour called Do The Math, which has held events in more than 20 cities across the country in opposition to the pipeline. The event in Washington is billed as their biggest yet.
The first event is a show at the Warner Theater. From there, marchers will assemble at Freedom Plaza, before circling the White House.